Process and apparatus for the impregnation of fiber fleeces with binding agents



Jan. 11, 1944. c, 1 NOTTEBOHM 2,338,960

PROCESS AND APPARATUS FOR THE IMPREGNATION OF FIBER FLEECES WITH BINDING AGENTS Filed April 14, 1938 2 Sheets-Sheet l 21 6%. gym/W A; z/ffiw gg /n ventan' Jan. 11, 1944. Q NOTTEBOHM 2,338,960

PROCESS AND APPARATUS FOR THE IMPREGNATION OF FIBER FLEECES WITH BINDING AGENTS Filed April 14, 1938 2 Sheets-Sheet 2 Patented Jan. 11, 1944 PROCESS AND APPARATUS FOR THE IM- PREGNATION OF FIBER FLEECES WITH BINDING AGENTS Carl Ludwig Nottebohm, Weinheim, Baden, Germany; vested in the Alien Property Custodian Application April 14,1938, Serial No. 202,136 In Germany April 21, 1937 Claims.

The invention relates to a process and apparatus for the impregnation of fiber fleeces with binding agents in the form of foam. The processes known heretofore for the treatment of fiber fleeces with impregnating agents beaten to a foam possess the disadvantages that they produce irregular products owing to th formation of bubble and folds during impregnation, and in addition are not suitable for the manufacture of impregnated fiber fleeces of any desired thickness.

It has now been found that fiber fleeces can be impregnated with binding agents in the form of foam, while avoiding these disadvantages, by impregnating two fiber fleeces at first each independently with the binding agents in the form of foam, and thereupon assembling and pressing them together, further binding agents in the form of foam being introduced between the assembled fleeces. Expediently, the process is carried out by combining in one working operation the impregnation of the individual fleeces and the assembling thereof, accompanied by further impregnation.

As starting materials for the new process, fleeces or the like structures of natural or artificial fibers are employed. It is possible to employ animal hair, for example wool, animal fibers, for example silk, skin fibers or leather fibers, vegetable fibers, for example cotton, bast fibers, wood fibers, mineral fibers, for example asbestos, or artificial fibers, for example artificial silk. The fibers may be subjected to various pre-treatments according to the nature or quantity of the impregnating agent to be absorbed by the fiber fleece. It is possible, for example, to open up the fibers by boiling, to treat them with oxidising or reducing agents or to impregnate them with wetting agents.

The fibers, pre-treated or not pre-treated, are passed through a carding machin or lik apparatus and worked up into a continuous fleece. The fibers may be carded loose or wide and after carding may be more or less strongly pressed.

As binding agent, use is made of solutions, emulsions or suspension, beaten to a foam, of natural rubber, such as latex, or of reclaimed rubber, of rubber-like substances, of nitro-cellulose, of artificial, in particular thermoplastic and reversibly thermoplastic resins, such as polymerisation compounds or mixed polymerisation compounds of unsaturated organic compounds, in particular DOIy-acryl compounds, polyvinyl compounds or polystyrols, of drying or semi-drying oils, of bitu mens, of water-soluble adhesives, such' as glue, gelatin tragacanth and other proteins, of binding agents of an inorganic nature, such as water glass or their mixtures. Such foam mixtures may be made from the aqueous solutions of the bindin agents or from solutions of organic solvents. It is particularly advantageous to use emulsions or dispersions.

In order to facilitate the foam formation, it is possible to add to the binding agent mixtures substances which reduce the surface tension of the solution or of the disperse phase, for example saponins, glucosides, proteins, decomposition products of carbohydrates and glue, for example mixtures of highly heated sugar with gum arabic, alkali lactates and the like.

If necessary, it is possible to add to the binding agents additional substances, vulcanisation agents, vulcanisation accelerators, softeners, coagulators, for example substances imparting sensitiveness to heat, such as ions of dior trivalent metals, fillers, such as kaolin, bentonites and the like, which have a consolidating or stiffening action on the foam mass. Furthermore, thickening substances, such as gelatin, methyl cellulose, glue, tragacanth, tragesol and the like may be added.

The binding agents and the additional substances are beaten to a foam in a planet agitator or similarly acting apparatus.

The use of the binding agents in the form of foam possesses considerable advantages. By employing foam, the emulsions or dispersions or even solutions may be mixed with very much less, approximately up to 25% less liquid, without impairing the impregnating properties. By this means, the drying time of the impregnated fiber fleeces can be considerably reduced. In consequence of the light weight of the masses in the form of foam, volumetrically larger quantities of binding agents can be introduced between the fleeces than in the case of th use of liquid binding agents. The feeding of the binding agents in the form of foam can be effected much more easily. Also, there is only a slight loss of impregnating substance during the impregnating operation, because th binding agent in the form of foam cannot flow away so easily at th outer edges of the fleeces. Finally, less attention has to be paid to uniform impregnation than in the case of liquid dispersions or emulsions. In order fully to utilise these advantages, care will preferably be taken to see that the foam structure of the binding agent is preserved during the entire impregnating operation.

The fleeces are impregnated with the binding agents in the form of foam in an apparatus in which, accordizig to the invent-loll, they im pregnatecl independently then ,iointl 21ml assembled. Such apparatus comprises fundamentally at least two movable supports, each of which serves for receiving and carrying a single fleece, spreading devices disposed above said supports for impregnating individual fleeces and a. pressing device comprising two ele ments pressihg against one another, between which elements the individual fleeces are assembleci. As movable supports for receiving the i:idiviclual fleeces, it is possible to employ in the first place rollers, furthermore, conveyor or slat type conveyors. As spree-ding devices, rollers spreading bonds or spreading doctors preferably be employed. The pressing device comprises pair of rollers or pail: conveyor bands. if rollers are used, they may be heated if desired. ere ezzpeilien'tly constructed in the 502m of sieve rollers order carry 023i excess oi binding agent during the oporation.

The fiber fleeces may be moves, towards one another, for example, on endless conveyor bands arranged horizontally or obliquely at any desired angle to one another, or on rollers, and impregnoted in such a manner with the binding agent beaten to a foam biocliug agent first brought on to each individual fleece, then introduced between the ass :uibletl iceces.

An apparatus accord" g to vezition is shown in Figure l. libel fleeces 3 ried towards one another on endless conveyor bands 2 disposed obliquely to one another guided over rollers 2. Above the conveyor ends 2 are spreading rollers by means whereof the binding agent 5 in the form of foe pressed into the fiber fleeces. lhe g mated fleeces are assembled cg, ein the gap between the rollers c. further impreg noting agent 5 in the form of foam being du-ced between the fleeces. The fleeces, jointly impregnated and pressed together, are carries away from the roller gap in the form of a con tinuous band I. More than two fiber fleeces may also be impregnated in this way. For example, as indicated in the dotted part of Figure i it is possible, in place of two fiber fleeces, to impregnate four fiber fleeces first each independently on conveyor bonds by means of spreading rollers and thereupon to unite them in the pressing device In a particularly expedient construction of the apparatus according to the invention, the elements of the pressing device, for example rollers or conveyor bands, serve simultaneously as sup ports for the impregnation of the individual fleeces. This construction is shown in Figures 2 and 3. In Figure 2, the impregnating apparatus comprises two adjacent horizontal rollers 8 adapted to be moved towards and away from one another by means of the adjusting device 9 and two smaller rollers In which are mounted vertically above the first-mentioned rollers and which are held loosely in the guide H and rest on the large rollers 8. The two fiber fleeces 12 are passed over rolls I3 and in each case between two superimposed rollers IB and 8, the rollers l0 pressing the impregnating agent II in the form of foam into the fleeces. The individually impregnated fleeces are then united between the adjacent rollers 8 to form a total fleece l5, further binding agent I4 being introduced between the individual fleeces. The width of the gap between the large rollers 8 may be adjusted according to the dewal assume sired. pressure of application. The small rollers E55 press the binding agent into the fiber fleece only by their own weight. They may be exchanged ior rollers of different weight, in which case, according to the weight, the impregnating agent penetrates the fiber fleece to a, greater or less depth. With a working width of the rollers ill of 14.8 centimeters, ioi' impregnating fleeces of about ll grams Weight per square meter, rollers weighing Gto lilkilograms are used, for impregnating fleeces of 89 grams Weight per square meter, rollers weighing 30 to 50 kilograms are used and for impregnating fiber fleeces of 100 grams weight per square meter, rollers Weighing to 126 kilograms are used. The upper rollers ill say be driven not only by friction on the under lying; rollers, but also by a separate driving device.

Figure 3 shows another construction in which the elements of the pressing device simultaneously serve as supports for the individual. fleeces. Here, the two fleeces Eli are brought together on two endless conveyor bands ill carried over rollers ii. The impregnating agent l8 is introduced in the first place between the spreading doctors 2i! and the individual fleeces l8 and is distributed on the surface of the latter, and in the second place is introduced between the two assembled fleeces. A uniform, homogeneously impregnated fleece ii is led away from the roller gap.

The process and devices according to the invention ensure numerous advantages. The r peateol impregnation results in very uniform products, the combined impregnation of the as semblecl fleeces serving to complete the impreg nation of the individual fleeces. The individual-- 13 impregnated. fleeces are applied smoothly to the surface oi the pressing device, any formation 01 bubbles or tongues through air inclusions ing avoided Finally, the invention permits the simultaneous impregnation of a plurality of fleeces with different binding agents. In this case, for example one surface of the fiber fleece to be impregnated, for example the upper sur-- face may be treated with certain binding agents imparting adhesion of lacquer or coloured binding agents, closing the surface as for as possible, am; the other, for example the lower surface, may be treated with colourless or differently coloured binding agents, more particularly adhesive bin ilug agents.

Typical means for this purpose are illustrated in Fig. 1, where the fleece 3, before reaching the endless band support 2 is coated on its lower side by the spray 28 and then passed over the dryer 25. Where the upper surface is to be coated also then similar devices will be provided above the fleece 3. Similar means are provided for the arrangements illustrated in Figs. 2, 3 and 4.

Frequently, the fiber fleeces to be impregnated do not possess sufficient strength, and may be damaged in their fiber structure in the impregnoting mechanism. In such cases, it has been iound expedient, before impregnation, to treat the fleeces with strengthening and adhesive agents in quantities such that, after drying, there is formed a surface which is close as possible and which, on the one hand, imports to the fleece a certain firmness and, on the other hand, prevents the binding agent employed during impregnation from passing through and hence prevents soiling of the supports carrying the fleeces. Preferably adhesives which are water-insoluble or even water-repellent are employed. 7 If such pre-treated and dried fleeces are employed as starting material, it is possible during the impregnation with binding agents in the form of foam to ensure that impregnation only takes place on the outer surface closed by the pretreatment. In this case, the pre-treated fleeces are assembled in such a manner that the pretreated sides of the fleeces are on the outside. In this case also, the fleeces are first impregnated individually and thereupon assembled and pressed together, further binding agents in the form of foam being introduced between the assembled fleeces.

In general, double impregnation is suflicient for ensuring uniform products. In some cases, however, it has been found that, despite double impregnation; the binding agent does not penetrate sufliciently deeply and uniformly the fiber fleeces to be impregnated. This is to be attributed to the fact that the binding agent in the form of foam, which is applied to the individual fleeces in the first impregnation, does not wet the surface of the fleeces sumciently.

It has now furthermore been found that for the purpose of ensuring good and thorough impregnation even with the first impregnation,

the individual fleeces, after impregnation, should each be pressed independently and only then assembled. This may be done by arranging between the spreading device and the pressing device, in which the fleeces are assembled, at least one further pressing device for the individual fleeces. According to this construction, each fleece impregnated by means of a spreading roller or spreading doctor is introduced into a pressing device, for example is passed between two rollers, before being assembled with another fleece. The device to be employed for this purpose is particularly expediently constructed in such a manner that the spreading device for the individual fleece is formed at the same time as an element of the pressing device for the individual fleece.

Such a. device may, for example, comprise three superimposed, horizontal pairs of rollers 22, 23 and 24. The fiber fleeces 25 are first passed between the rollers 22, 23, the impregnating mass in the form of foam being introduced between the rollers 23 and the fiber fleeces. The binding agent is pressed into the fleeces by the spreading rollers 23. Thereupon, each fleece is passed round substantially half the upper roller 23 and is taken ofi by asuperimposed counter-running roller 24 after the manner of the clearer of a carding machine. also exerted on the outwardly turned side facing away from the impregnating agent during inoividual impregnation, said pressure effecting a more intimate impregnation of the fiber fleece with the impregnating material. The individual fleeces passed round the rollers 24 are then assembled between the rollers 22, further binding agent being introduced between them. A uniiormly impregnated total fleece 21 is led away from the gap between the rollers 22.

The various rollers of such an impregnating apparatus will expediently be selected differently. In some cases, the diameters of the rollers diminish upwardly as shown in the figure. In other cases, conversely, it is preferable to arrange the iollers withthe largestdiameter at the top. The mounting of the rollers will preferably be such that the angle included by the assembled fleeces is as acute as possible. A better distribution of the foam material on the By this means, a pressure is 5 surface of the assembled fleeces is thereby ensured, which again produces a more uniform impregnation and prevents the forming of pouring folds or creases.

Of course, other pressing devices may be provided instead of the top rollers 24. Likewise, it is possible to mount a plurality of pressing rollers 'one above the other and the individually pre- Example For uniformly impregnating two fiber fleeces centimeters in width and about grams weight per square meter without creases and without tongue formation, they are introduced into an apparatus according to Figure 2. The horizontally mounted pair of rollers 8 have. a diameter of 30 centimeters. The upper horizontally mounted pair of rollers have a diameter of about 10 centimeters, a width of 1.40 meters and a weight of about 120 kilograms. The two fiber fleeces are introduced respectively from the sides between a pair of rollers l0 and 8. Between the fleeces and the rollers III, the binding agent in the form of foam of the following composition is introduced:

(marketed under the trade name of Corealgrund) "parts" 250 Gelatin do 20 A 50% solution of a lauryl alcohol solution parts 250 Tricresyl phosphate do 13 A 50% saponin solution do 50 Emulsifier do 1 Casein solution per cent-.. 10

From 10 litres of this solution, 35 litres of foam- Parts 60% latex Accelerator 2 Sulphur- 1 Zinc oxide 2 A 3% wetting agent solution 400 A 50% saponin solution 15 Indanthrene dyes 5 A 5% vultamin solution 10 10 litres of this mixture produce about 25 litres of foam after beating for about 5 minutes. The fleece impregnated for a second time leaves the rollers 8 at a rate of about 2 meters per minute and can be passed thence to further treatments. It is completely impregnated throughout and is conspicuous for its smooth surface and freedom irom creases.

The resulting impregnated product, if desired after further pressing and dressing, may be employed as artificial leather, floor covering, furniture covering material or motor car covering material.

I claim:

l. A process for the complete, thorough impregnation of unwoven fibrous fleeces with binding agents in the form of foam which comprises treating the individual fiber fleeces on one side superficially with adhesive substances in such quantities that after drying a surface is formed which is as close as possible and which prevents penetration therethrough of the binding agent employed in the subsequent complete thorough impregnation, drying the pretreated fleeces, impregnating the fleeces thus pretreated and dried individually by treatment with binding agents in the form of foam on the untreated side, assembling at least two of the pretreated and impregnated fleeces in such a manner that the pretreated sides of the fleeces are on the outside, while introducing further binding agents in the form of foam between the fleeces and pressing them together so tightly that structures, which are uniformly impregnated throughout, are obtained.

2. A process for the complete, thorough impregnation of unwoven fibrous fleeces with binding agents in the form of foam which comprises treating the individual fiber fleeces on one side superficially with adhesive substances in such quantities that after drying a surface is formed which is as close as possible and which prevents penetration therethrough of the binding agent employed in the subsequent complete thorough impregnation, drying the pretreated fleeces, impregnating the fleeces thus pretreated and dried individually by treatment with binding agents in the form of foam on the untreated side and after impregnation pressing them for better impregnation, and thereupon assembling at least two of the pretreated and impregnated fleeces in such a manner that the pretreated sides of the fleeces are on the outside, while further binding agents in the form of foam are introduced between the fleeces and pressing them together so tightly that structures which are uniformly impregnated throughout are obtained.

3. A process as claimed in claim 1, wherein the individual fiber fleeces are impregnated with binding agents of difierent composition.

4. A process as claimed in claim 1, wherein the individual fiber fleeces are impregnated on one side with water-insoluble adhesive substances.

5. A process as claimed in claim 1, wherein the individual fiber fleeces are impregnated on one side with water-repellent adhesive substances.

CARL LUDWIG NOTTEBOHM. 

